Several attempts have already been made to achieve the possibility of controlling the position of a stent in a delivery device during the placement operation, before its full length becomes radially expanded.
U.S. Pat. No. 5,026,377 discloses a stent delivery device for a self-expanding stent such as the one disclosed in U.S. Pat. No. 4,665,771. The proximal end of the stent to be released is fastened to a central pusher of the device either by an adhesive, or by a local widening of this pusher.
WO 96/13228 discloses a stent delivery device provided with a soft "recapture sleeve"--generally bearing crossed grooves--located on the central pusher of the device in order to prevent axial displacement of a self-expanding stent relative to the pusher before a given fraction of the length of the stent has been allowed to expand.
In practice, however, these devices do not provide fully reliable results.
Just before its deployment in the vessel, the stent is located inside a chamber toward the distal end of the delivery device. Once the stent has been partially deployed and hence allowed to expand, it places itself against the interior wall of the vessel. It proves difficult to force it back into the chamber. Indeed, instead of entering back the chamber, the stent is often ripped out of the end of the delivery device and thus can no longer be displaced without being destroyed or removed by surgery.
Furthermore, the recapture means of the devices according to the state of the art add to the radial cumbersomeness of the delivery device.
There has therefore been a strong need for a space-saving and efficient reversible-action endoprosthesis delivery device.